Electric switch



1,519,061 A. w. SCHRAMM ELECTRIC SWITCH Filed July 15, 1921 Patented Dec. 9, 1924.

ADOLIPH W. SCHRAMM, 0F RIVEitTON, NEW JERSEY, ASSIGNOR TO ELECTRO DENTAL 1,519,051 PATENT OFFICE.

MANUFACTURING- COMPANY, or IPHILADELPHIA, PENNSYLVANIA, A ConronA- 'IION OF PENNSYLVANIA.

ELECTRIC swrrcnl Application filed l'uly 13, 1921. Serial No. 484,355.

tacts positioned to Cooperate with a single movable contact for permitting current flow "in any of a number of circuits oi in any of the branches of the same circuit. and one object of said invention is to provide a switch whose construction shall be such as to prevent the possibility of the movable contact simultaneously engaging any two part or parts of the movable Contact co-' operating therewith :the construction being such as to insure the high speed disengagement of the movable contact from each of the fixed contacts and its immediate engagement with another and adjacent fixed Contact so that any flash or are produced is reduced to a minimum.

The invention also contemplates a quick break multi-point switch having the above.

named characteristics. which will make impossible the short circuiting of the adjacent fixed contacts by the movable contact regardless of the direction of the movement of the latter, and whose construction shall be relatively durable, simple, ,compact and inexpensive as well as not likely to get out of order nor require any but a minimum of attentionand repair.

1n electric switches associated with rheostats and similar apparatus, it has hitherto been customary to so arrange and construct the parts that the movable contact member will either short circuit two adjacent fixed contacts or will be of such dimensions as to be incapable of simultaneously engaging two such contacts and will consequently break the circuit in which it is included. Another object of my invention is, therefore, to provide an" electric switch at such.

[strip or, plate 6 constitutin construction that the movable contact member cannot at any time short-circuit or simultaneously engage two adjacent fixed contacts, nor be moved into a position in which it will break the circuit in which it is included or in which it does not en age one of the fixed contacts.

These objects and other advantageous ends I attain as hereinafter set forth, reference belng had to the accompanying draw- 1ngs, in which,

Fig. 1 is a plan of a switch constructed in accordance with my invention:

..F1g. 2 is a vertical section on the line 22, Fig. 1;

Figs. 3 to 12 inclusive are vertical sectrons on the line 3-3. Fig. 1. showing diagrammatically the movable contact memher in certain of its different operative positions relatively to the fixed contacts Fig. 13 is a perspective view of one of the fixed contacts; Figs. 14 and 15 are perspective views of the free end of the movable contact:

Fig. 16 is an elevation of one end of one of the fixed contacts;

Flg. 17 is a perspective View of the free end of .a special form of movable Contact;

Fig. 18 is a plan, to some extent diagrammatic, showing a modified form of my invent-ion; and. r

Fig. 19 is an end elevation of the movable contact.

In the above drawings. 1 represents a suitable base or supporting structure of insulating material including, in the case illustrated, a circularly curved strip 2 projecting from one face and serving to support a. series of fixed metallic contacts 3 above the level of the main portion of said base. These are held to said strip in the present instance by screws 4 which may serve as binding posts, although obviously electrical-conductors may" be connected to these contacts in any way desired without departing from my invention.

' In accordance with my invention each of the fixed contacts 3 is made of relatively stiff metal strip or plate such as brass, and

are arranged on their supporting structure 2 concentrically with a spindle 5 which has fixed to it a radially projecting metallic the movable contact of the switch. Eac of the fixed contacts projects inwardly from the support- I ing structure 2 toward said spindle 5 and a lever.

' contacts lie in a plane above and parallel with a plane including their right sides, while the top and bottom faces of said contacts are approximately plane and parallel.

-The movable contact 6 inthe present instance is connected in any suitable'manner ,to the spindle 6 which likewise has fixed to it an operating handle or head 8 and is' rotatably mounted in the supporting structure 1 where it is held by a pair of retaining nuts 9 and 10. The nut 10 serves to.

electrically connect a suitable conductor to the spindle .and therefore to said movable contact, although obviously the latter may be connected into a'circuit by any other suitable means withoutdeparting from my in- I vention.

Said contact 6 is peculiar in being formed of a more or less springy metallic plate or strip whose outer or free end is split or forked to form two contact engaging fingers 12 and 13 each of which is twisted or bent so that it mayengage and lie parallel with either the top orthe bottom faces of the projecting portions? of the fixed contacts. These fingers are vertically separated by a space whose width is somewhat less than the thickness of the rojecting portions 7 of the fixed contacts w ich are bent to such an extent that the perpendicular distance between any two adjacent contacts is greater than the thickness of the fingers 12 and 13. Two stops 14 and 15 are provided on the supporting structure 1 to.limit the movement to said movable contact as the spindle J is turned by means of the head 8.

With the above described arrangement of parts, the strip or plate constituting the movable contact 6 is preferably mounted on the spindle so that itlies in or tends to readjacent fixed contacts.

are sprung upwardly out of their normal plane so that the second finger 12 projects at a higher level than the finger 13.

If now the handle8 be moved in such a direction as to cause the contact 6 with its fingers to move in the direction of the arrow (Fig. 3), the finger 13 slides downwardly on and in electrical contact with the top face of the fixed contact 3 which it engages,-

and as it so moves the level of the finger 12 is lowered so that its advancing edge engages and is moved down by. the bevelled left hand edge of the same fixed contact as shown in Fig. 4. As a result, as the movement of the handle continues, the finger 12 passes-onto and in full engagement with the under face of said contact; the first finger 13 lying immediately under the projecting portion 7 of another fixed contact but being held out of engagement therewith (Fig. 5) because of its connection with the relatively stiff yet springy movable contact strip which however, 'is now sprung below its normal plane or position of repose.

The continued movement of the handle still further springs the movable contact strip 6 below its normal plane until when its'fingerv 12 finally passes off of the first fixed contact 3", it is instantaneously snapped or moved therefrom into engagement with the under side of the second fixed contact 3'? (Fig. 7) which is clearedby or spaced away from the finger 13. The latter however by reason of'the stiffness of the mov able contact strip, cannot move into engagement with the under side of the third fixed contact 3, and as the handle 8 is further turned from left toright. the finger 12 successively snaps from engagement with the underside of each fixed contact ontorthe underside of that next adjacent it, in each .case instantaneously breaking any current flow between-it and said contact but without at any time simultaneously engaging two The second finger 13 remains spaced away from the fixed contacts during such movement and operation.

If now the direction of movement of the head or handle 8 be reversed so that it is turned in a counter clockwise direction, the left hand edge of the finger 13 comes into turn to the general plane of the fixed conengagement with and slides upwardly first tacts 3, for which purpose'a washer 16, of the same thickness as the contact-supporting R structure 2 is placed on the spindle 5 between said contact strip and the top face of the supporting structure 1.

In assembling the parts of the device made as above described, the finger 13 of the movable contact 6 is placed upon the top'face of any one of the fixed contacts 3, for example, as indicated in Fig. 3, that one at the extreme left hand end of the series. Under these conditions, the body of said movable contact as well as its two fingers on the bevelled edge or side of the nearest one of the fixed contacts 3 on its left side and then onto the flat top face thereof 8 and 9), while the finger 12 similarly slides upwardly in engagement with the under face of the same fixed contact. After the finger 12 disengages this under face, it continues to rise above the plane of the fixed contacts as the finger 13 slides upwardly over the top face of the fixed contact 3 for example (Fig. 10) until it finally snaps off of the highest portion of said fixed contact and instantaneously thereafter comes into engagement with the top face of. the first fixed contact 3* upon which it may be moved upwardly until further counterclockwise movement of the movable contact is prevented by its engagement with the stop 15'.

Regardless therefore of the position of the movable contact 6, its finger. 12 if moved in a clockwise direction, will successively but independently engage the under faces of the fixed contacts to the right of it and if its direction of movement be reversed itsfinger 13 will slide into engagement with the top face of that fixed contact last engaged by the finger 12 and will thereafter successively and independently engage the top faces of the fixed contacts to the left as its movement is continued. Obviously at no time is it possible for either or both of the fingers of the movable contact to simultaneously engage two of the fixed contacts, and its construction is such that it necessarily moves from one of the latter into engagement with the other at a relatively high speed, dependent upon its own resiliency and the proportions and dimensions of the various coacting parts. There is therefore practically. no arcing between contacts owing to the quick brcaks invariably made and there is no possibility of a movable contact making any but a quick and good contact with each fixed contact which it engages. g

It should be particularly noted that the portions 12 and 13 of the movable contacts are both of a greater width than the width of the spaces between the fixed contacts, although by reason of the construction above described there is no possibility of the short circuiting of any two of said fixed contacts by the movable contact. The switch is therefore particularly adapted for use in connection with that class of electrical apparatus wherein it is not permissible to even; momentarily short circuit or permit connection of conductors leading to any adjacentapair of contacts.

If desirable or found advisable I may without departing from my invention protect the fingers 12 and 13 of the movablevcontact 6 from possibility of short ci'rcuiting two adjacent fixed contacts when moving between them from a position on one side of their plane to a position on the opposite side thereof. For this purpose 'I attach plates of insulating material 21 and 22 to said fingers as shown in Fig. 17, holding them in the desired position by rivets '20 or other suitable means. Obviously these protecting pl'atesor pieces of insulating material would be applied to those faces of the fingers 12 and'-13 which were not intended to make electrical engagement with the fixed contacts and in the case shown the insulating piece 22 could be applied to the upper face of the finger 13 and to the under face of the finger 12.

"It is to be noted that my invention is not shown in Fig. 18 and provide a movable contact having fingers which cooperate with said fixed contacts as hitherto described. In

Figs. 18 and 19 the fixed contacts 90 are shown as so-\formed or mounted as to lie in a cylindrical surface. A movable contact arm 91 is pivotally mounted at 92 and has projecting fr om its free end a resilient piece 93 carrying a pair of contact fingers 94 and 95 which as said arm is swung on its pivot, cooperate with the fixed contacts 90 as described in connection with the other form of my invention. of the movable contact, as with that shown in the foregoing figures, it will be noted that the operative-faces of the contact fingers are so arranged and mounted as to lie parallel with the face of that fixed contact which they engage at any given time,a valuable feature of theinvention insuring. good contact and avoiding heating.

. I claim:

1. The combination in an electric switch of 'a series of fixed contacts mounted to lie substantially within a plane; with a movable With this construction,

contact hav ng two portions formed and positioned to respectively engage opposite faces of the fixed contacts when it is moved in opposite directlons.

2. The combination in an electric switch of. a series of fixed contacts mounted to lie substantially within a plane; with a movable contact having two portions formed and po sitioned to respectively engage opposite faces of the fixed contacts when it is moved in opposite directions, said fixed contacts including portions cooperating with the movable contact to automatically shift its two engaging portions from one side to the other of'the plane of said fixed contacts.

3. The combination in an electric switch of a movable contact including two contact fingers; with a series of fixed contacts each having two faces for cooperation with the movable contact and each including a portion formed to cause one of said fingers to engage one of its faces when it is moved in one direction and to engage its other face when it is moved in the opposite direction.

4. The' combination in an electric switch of a series of fixed contacts mounted to lie substantially within a plane and each havsaid fixed contacts. and said movable con- Ill tact hearing such relation that the latter may snap from engagement with one fixed contact into engagement with another.

5. The combination in an electric switch of a seriesof fixed. contacts each having two opposite faces; with a movable contact formed to engage either face of said fixed contacts and free to move between two of the latter and maintain the circuit closed when its direction of movement is reversed, said contacts being so related that said movable contact may instantly snap from one fixed contact toanother.

6. The combination in an electric switch of a series of fixed contacts of a movable contact including two contact fingers laterally displaceable by the fixed contacts and free to engage opposite faces thereof re; spectively when the direction of the movable contact 'is reversed.

7. The combination in an electric switch of a supporting structure; aseries of fixed contacts mounted thereon and each including a projecting portion having oppositely placed flat faces lying at an acute angle to the plane of the fixed contacts and each also having'relatively sharp side edges; a movable contact having two resiliently supported contact fingers free to pass between the fixed contacts and formed to'be automatically shifted from one side of the plane thereof to the other side of said plane when the direction of movement of the movable contact is reversed.

8. The combination in an electric switch of a series of relatively fixed contacts; a movable contact having two fingers for engagement with-the fixed. contacts, said fingers and thefixed contacts being all inclined to the plane of movement of the movable contact and said fingers being free to pass from one side of the plane of the fixed contacts to the other side thereofwhen the direction of-motion of the movable contact is reversed.

9. The combination in an electric switch of a series of fixed contacts each having a projecting portion; with a movable contact having fingers formed to electrically engage the opposite faces of 'said projecting portions of the fixed contacts, and both free to pass from one side tothe other of the plane of said contacts'when their direction of movement is reversed. j

10. The combination in an electric switch of a series of fixed contacts each having double contact faces; a movable .contact having two fingers formed to respectively engage opposite faces of said fixed contacts and both shiftable from one side to the other 'of the line of the fixed contacts when the direction of movement of the movable contact is reversed. t

11. The combination in an electric switch of a series of fixed contacts each having double contact faces'lying in inclined parallel planes; with a movable contact having a pair of contact fingers formed to respectively cooperate with the two faces of said fixed contacts and shiftable from one side to the other of the line of said fixed contacts when the direction of movement of the movable contact is reversed; with insulation covering one side of each of said.

fingers.

12. The combination in an electric switch of. a series of .fixed contacts each having double contact faces lying in inclined parallel planes; with a movable contact having a pair of contact fingers formed to respectively cooperate with the' oppdsite faces of said fixed contacts and shiftable from one side to the other of the line of said fixed con tacts when the direction of movement of the movable contact is reversed; with insulating material on one side of one of said'fingers and on the opposite side of the other finger.

13. In an electric switch, the combination with a series of fixed contacts each having a portion lying at an acute angle to the line of such series; of a movable contact having a pair of fiat fingers twisted to lie substantially parallel with the inclined portions of said fixed contacts.

14. An electric switch comprising aseries of fixed contacts, each contact having a portion inclined at an acute angle to the line of such series; and a movable contact comprising a pair of fingers twisted to lie substan-' tially parallel with the inclined portions of said fixed contacts, said fingers being spaced a distance substantially equal to the thickness of said inclined portions of said fixed contacts.

15.. An electric switch comprising a series of fixed contacts mounted to lie substantially within .a plane: said fixed contacts having'portions inclined at an acute angle to said plane; anda movable contact having a pair of fingers twisted to lie in planes substantially parallel with the planes ofthe inclined portions of the fixed contacts, said contact fingers being spaced ver tically and horizontally.

' ADOLPH w. scHRAmi; 

